1. Field of the Invention
The present invention relates to a display device and fabricating method thereof. More particularly, the present invention relates to a liquid crystal display device and fabricating method thereof.
2. Description of the Related Art
With big advance in electronic technologies, digital video products or imaging devices has become one of the most common electronic gadgets in our daily life. Among various video products and imaging devices, display devices inarguably occupy a central position because a user must extract information from a display device, or in the case of performing a real-time control, receive real-time data from a display device.
To fit the lifestyle of modern day people, the size and weight of video and imaging products must be reduced as much as possible. Although cathode ray tubes (CRT) still has some advantages, bulkiness and volume are the two major setbacks that reduce its popularity in the future. With breakthroughs in photo-electronic and semiconductor fabrication technologies, panel type displays such as the liquid crystal displays are starting to replace the conventional CRT because of its low operating voltage, radiation free operation and light-weight and streamline body. In fact, researches in liquid crystal display and other flat panel displays such as plasma display panel and electro-luminance displays have dominated the field in recent years due to its potential as a mainstream product in the market.
In general, a thin film transistor (TFT) liquid crystal display comprises a thin film transistor array substrate, a color filter substrate and a liquid crystal layer. FIG. 1 is a schematic cross-sectional view of a conventional liquid crystal display panel. The liquid crystal display panel in FIG. 1 comprises a color filter substrate 100, a thin film transistor array substrate 102, a sealant 104 and a liquid crystal layer 106. The liquid crystal layer 106 is enclosed within the space bounded by the color filter substrate 100, the thin film transistor array substrate 102 and the sealant 104. The color filter substrate 100 further comprises a color filter 113 and a black matrix 114. Furthermore, the thin film transistor array substrate 102 comprises a display region 108 and a non-display region 110. The non-display region 110 has a plurality of lead lines 112 serving as drivers for operating the display device.
To form the liquid crystal layer 106, the sealant 104 is placed between the substrates 100 and 102 to form an enclosed space. Thereafter, a small quantity of liquid crystal is gradually filled into the space between the color filter substrate 100 and the thin film transistor array substrate 102 under a capillary effect due to the presence of an external atmospheric pressure. Because the injection speed of liquid crystal under capillary effect is slow, other injection techniques such as the one-drop fill (ODF) process is deployed. In the one-drop fill process, a layer of UV sealant is coated on the thin film transistor array substrate 102 (or the color substrate 100) to form a sealant 104. Each drop of liquid crystal is dropped inside the area enclosed by the sealant 104. Thereafter, the color filter substrate 100 (or the thin film transistor array substrate 102) is placed over the sealant 104. The sealant 104 is illuminated with UV light so that the sealant 104 hardens so that the sealant 104 bonds the color filter substrate 100 and the thin film transistor array substrate 102 together.
Using the ODF technique, time for injecting liquid crystal into a liquid crystal display panel is reduced considerably. For example, only 2 hours are required to fill a 30 inches panel using the ODF technique. If the same display panel is filled using the capillary injection technique, roughly five days are required. Hence, production time is shortened considerably. Furthermore, ODF technique requires only 40% of the liquid crystal needed in a capillary injection process. However, care must be executed to prevent any contamination of the liquid crystal by the sealant that may lead to liquid crystal display problems. In general, the black matrix (BM) 114 on the color filter substrate 100 has to move a definite distance toward the central area of the panel. With the black matrix (BM) 114 moved from the edges, a strip of area 116 adjacent to the edge is no longer covered with any barrier. Since the gap between lead lines 112 in the non-display region 110 has no barrier, light can easily leak from the edge of the display panel.